Primary cells



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PRIMARY CELLS Gwen David Lucas, Berrystead, Ascot, England Y Application August 18, 1952, Serial No. 305,083

' 16 Claims. (Cl. 136-100) The invention is an improved means whereby the output of electrolytic, and particularly primary cells can be substantially increased.

According to the present invention, the output of an electrolytic cell is substantially increased by introducing hydrogen peroxide into the electrolyte so that the material of the anode (i. e. the internal positive electrode) of the cell is contacted by the hydrogen peroxide.

No attempt can be made to give a definite explanation of the reason why the outputA of the cell'is improved by adding hydrogen peroxide, but both the open circuit voltage of the cell and the current output are so very greatly improved in many cases that the hydrogen peroxide could not be'acting merely as a depolarizer. It is thought that thehydrogen peroxide both acts as a depolarizing agent and takes part in a main reaction, which appears to be quite separate from and generally more powerful than the normal main reaction of the cell. In View of this, it has been found desirable to reduce the normal main reaction to av minimum so that the hydrogen peroxide reaction predominates.

Although the action of the hydrogen peroxide is not fully understood, it appears to attack anodes of active metals to form the hydroxides of such metals, and it is thus preferred to use the invention with a cell in which the material of the anode is such as to be readily oxidizable by hydrogen peroxide under the cell conditions.

lt has been found that the hydrogen peroxide should generally not be introduced into the cell before the electrolyte since, if the hydrogenperoxide contacts the anode before the electrolyte contacts the anode, hardly any output may be obtained at all, at least in the iirst instance.

The output of the cell depends on the amount or rate of feed of hydrogen peroxide. Adjustment of the feed rate gives a ready means of controlling the output of the cell. It is generally preferred to use hydrogen peroxide of a substantially high concentration, e. g. 30% concentration. It has been found that -18 c. c. of 30% H2O2 may be sutlicient to give 1 watt-hour.

Many combinations of electrolytes with various electrodes may be used. Especially suitable are magnesium anodes with inert cathodes, such as rustless steel or silver using magnesium chloride as electrolyte with or without a proportion of ammonium chloride. Also suitable are aluminum anodes with similar or copper or carbon cathodes, using electrolytes such as caustic soda, ammonium chloride or aluminium chloride.

It has been found advantageous in many cases to add hydrochloric acid, or less preferably ammonium chloride, to the electrolyte as well as the hydrogen peroxide. The action of the'hydrochloric acid or ammonium chloride seems to be that it reacts with the hydroxide of the anode metal to produce the chloride of such metal, which chloride may then act as fresh electrolyte. Alternatively, precipitates of such hydroxides may be removed from the electrolyte by filtration and then optionally treated with hydrochloric acid. The invention is illustrated in the accompanying drawings in which:

Figs. 1, 2 and 3 schematically illustrate processes embodying my invention; and

Fig. 4 is a perspective view of an electric cell in which the process of my invention may be carried out.

The following example illustrates the construction and working of a cell according to the present invention:

A cell is constructed with seven rustless steel plates whose immersion surface is about 5 x 4 each as shown in the typical example illustrated in Fig. 4. In between States., Patent O these and with about 1/16" clearance are placed six high purity magnesium plates with the same immersion area,

the purer the' magnesium the better the results obtained.v

The electrolyte used is magnesium chloride solution in a concentration to give its minimum ohmic resistance, which is about 400 grammes of the hydrated magnesium chloride per litre of water.

The electrolyte is contained in a reservoir at a lower level than the cell and is pumped continuously into the bottom of the cell, and overilows from a pipe near the top of the cell, whence it returns to the reservoir. The electrolyte is circulated in this manner through the cell at the rate of 6 to 8litres per hour. Figs. l, 2 and 3 schematically illustrate the process embodying my invention and I have illustrated the several components employed in the process, by legends, in the block diagrams shown in thev several views. Figs. 1, 2 and 3 illustrate different ways in which the components may be assem-V bled in carrying out the process of my invention.

The cell constructed in this manner gives an open circuit voltage of 1.6 volts, and a current of about 7 am peres at one volt which rapidly drops practically to zero.

Hydrogen peroxide of 30% concentration in Water, in which may be dissolved enough magnesium chloride to prevent dilution of the electrolyte, is added to the electrolyte at or near to the point where it-enters the cell, the rate of feed of this added solution being about 800 c. c. per hour. On the introduction of this hydrogen peroxide solution, the open circuit voltage of the cell rises at once to 1.82 volts and a steady current of over 70 amperes at over one volt is obtained. After a short period the open circuit voltage of the cell rises to just over 1.8 volts. This can be continued until the magnesium platesfhave been nearly used up.

It is found that the consumption of magnesium is from cipitate can be removed as previously described, e. g. by

adding 10% by volume of hydrochloric acid to the electrolyte, or by providing a filter in the electrolyte circulating circuit. Actually, it is found that the magnesium hydroxide does not interfere seriously with the performance of the cell except during long runs, since it ilows out of the cell into the electrolyte reservoir.

There is normally no change in the electrolyte except for the possible accumulation of impurities, but since these are mainly copper and iron which are also precipi tated as hydroxides, these can be removed by filtration.

When it is desired to stop running the cell, the circulating pump is stopped and the electrolyte will fall back into the reservoir through the bottom of the cell, so that the cell will be emptied of electrolyte automatically and no further action will take place. The addition of hydrogen peroxide is, of course, stopped at the same time. instead of circulating the electrolyte by pump, it may flow from a reservoir above the cell directly into the bottom of the cell and overflow into another reservoir below it.

In either circulating method, the electrolyte may be introduced into the top of the cell and pass out of the bottom of the cell under gravity to a reservoir at a lower level. An advantage of this arrangement is that the cell will automatically be emptied of electrolyte as soon as output from the cell is no longer required and the introduction of the electrolyte to the top of the cell is stopped.

I claim:

l. An electrolytic cell comprising a container enclosing an inert cathode, a magnesium anode and, an electrolyte containing magnesium chloride, means for introducing the electrolyte into the container, means for circulating the electrolyte through the container, and means for continuously feeding hydrogen peroxide from a reservoir into the electrolyte, substantially at the point where the electrolyte enters the container.

2. An electrolytic cell according to claim l, comprising also a compound selected from the group comprising hydrochloric acid and ammonium chloride added to the electrolyte.

3. An electrolytic cell according to claim l, comprising also means for filtering the circulated electrolyte.

4. An electrolytic cell comprising a container enclosing a copper cathode an aluminium anode, an electrolyte containing a compound selected from the group comprising ammonium chloride and aluminium chloride, means for introducing the electrolyte into the container, means for circulating the electrolyte through the container, and means for continuously feeding hydrogen peroxide from a reservoir into the electrolyte, substantially at the point where the electrolyte enters the container.

5. An electrolytic cell comprising a container enclosing a carbon cathode, an aluminium anode, and an electrolyte containing, caustic soda, means for introducing the electrolyte into the container, means for circulating the electrolyte through the container, and means for continuously feeding hydrogen peroxide from a reservoir into the electrolyte substantially at the point where the electrolyte I enters the container.

6. The process of operating an electrolytic cell including an anode, comprising substantiallcontinuously feeding hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by the hydrogen peroxide under the operating conditions of the cell and of continuously circulating the electrolyte.

7. The process as claimed in claim 6, when used wih an electrolytic cell the anode of which is magnesium and the electrolyte of which is magnesium chloride and the cathode of which is of inert material.

8. The process as claimed in claim 6, when used with an electrolytic cell the anode of which is aluminium and the electrolyte of which is a compound selected from the group comprising ammonium chloride and aluminium chloride and the cathode of which is carbon.

9. The process as claimed in claim 6, when used with an electrolytic cell the anode of which is aluminium and the electrolyte of which is a compound selected from the group comprising ammonium chloride and aluminium chloride and the cathode of which is copper.

10. The process as claimed in claim 6, when used with an electrolytic cell the anode of which is aluminium and the electrolyte of which is caustic soda and the cathode of which is carbon.

1l. The process as claimed in claim 6, when used with an electrolytic cell the anode of which is aluminium and the electrolyte of which is caustic soda and the cathode of which iscopper.

12. The process of operating an electrolytic cell including an anode, comprising substantially continuously feeding hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by the hydrogen peroxide under the operating conditions of the cell, continuously introducing the electrolyte into the top of the cell, and of causing the electrolyte to flow continuously from the bottom of the cell.

13. The process of operating an electrolytic cell including an anode, comprising substantially continuously feeding hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by the hydrogen peroxide under the operating conditions of the cell, continuously introducing the electrolyte into the bottom of the cell, and of continuously withdrawing the electrolyte from the tcp of the cell.

14. The process of operating an electrolytic cell including an anode, comprising substantially continuously feeding hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by the hydrogen peroxide under the operating conditions of the cell, introducing a compound selected from the group comprising hydrochloric acid and ammonium chloride, and continuously circulating the electrolyte through the cell.

l`5. The process of operating an electrolytic cell including an anode, comprising substantially continuously feeding hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by the hydrogen peroxide under the operating conditions of the cell, introducing a compound selected from the group comprising hydrochloric acid and ammonium chloride, continuously introducing the electrolyte into the top of the cell for circulating therethrough, and causing the electrolyte to liow continuously from the bottom of the cell.

16. The process of operating an electrolytic cell including an anode, comprising substantially continuously feeding'hydrogen peroxide into the electrolyte so that the material of the anode is readily oxidized by' the hydrogen peroxide under the operating conditions of the cell, introducing a compound selected from the group comprising hydrochloric acid and ammonium chloride, continuously introducing the electrolyte into the bottom of the cell, circulating the electrolyte therethrough, and continuously withdrawing the electrolyte from the top of the cell.

References Cited in the tile of this patent UNITED STATES PATENTS 615,172 Hess Nov. 29, 1898 898,055 MacMillan Sept. 8, 1908 1,160,133 Bliss Nov. 16, 1915 1,606,028 Head e Nov. 9, 1926 2,584,117 Elrod Feb. 5, 1952v FOREIGN PATENTS 291,166 Germany Aug. 1,. 1915 397,475 Great Britain Aug. 22, 1933 

1. AN ELECTROLYTIC CELL COMPRISING A CONTAINER ENCLOSING AN INERT CATHODE, A MAGNESIUM ANODE AND, AN ELECTROLYTE CONTAINING MAGNESIUM CHLORIDE, MEANS FOR INTRODUCING THE ELECTROLYTE INTO THE CONTAINER, MEANS FOR CIRCULATING THE ELECTROLYTE THROUGH THE CONTAINER, AND MEANS FOR CONTINUOUSLY FEEDING HYDROGEN PEROXIDE FROM A RESERVOIR 